A Novel Cooling Method for Turbine Rotor-Stator Rim Cavities Affected by Mainstream Ingress

2004 ◽  
Vol 127 (4) ◽  
pp. 798-806 ◽  
Author(s):  
Y. Okita ◽  
M. Nishiura ◽  
S. Yamawaki ◽  
Y. Hironaka
Keyword(s):  
Gas Flow ◽  
Numerical Study ◽  
Turbine Rotor ◽  
Rotor Blades ◽  
Significant Advance ◽  
Axial Distribution ◽  
Cooling Effectiveness ◽  
Cooling Flow ◽  
Cooling Method ◽  
Flow Phenomena

A combined experimental and numerical study of interaction between cooling flow and mainstream gas flow in a turbine rotor-stator rim cavity is reported. Particular emphasis is put on the flow phenomena in a rim cavity downstream of rotor blades. The experiments are conducted on a rig simulating an engine HP-turbine in which cooling effectiveness distributions as well as velocities, turbulence quantities, pressure, and temperature profiles are measured. Numerical calculation, especially at a full 3D, unsteady solution level, can lead to satisfactory predictions in fluid and mass transfer inside the cavity. Both experimental and numerical results indicate that large turbulence stresses near the rotor disk intensify turbulent diffusion across the cavity and consequently axial distribution of the cooling effectiveness inside the cavity becomes uniform. In order to obtain an adequate distribution of cooling effectiveness across the rim cavity and to suppress the turbulence level near the rotor surface for more efficient cooling, a novel cooling method is developed using numerical simulation. The disk-front and -rear cavities are then redesigned according to the new cooling strategy and integrated in the test rig. Experimental results verify a significant advance in cooling performance with the new method.

A Novel Cooling Method for Turbine Rotor-Stator Rim Cavities Affected by Mainstream Ingress

2004 ◽  
Author(s):  
Y. Okita ◽  
M. Nishiura ◽  
S. Yamawaki ◽  
Y. Hironaka
Keyword(s):  
Gas Flow ◽  
Numerical Study ◽  
Turbine Rotor ◽  
Rotor Blades ◽  
Significant Advance ◽  
Axial Distribution ◽  
Cooling Effectiveness ◽  
Cooling Flow ◽  
Cooling Method ◽  
Flow Phenomena

A combined experimental and numerical study of interaction between cooling flow and mainstream gas flow in a turbine rotor-stator rim cavity is reported. Particular emphasis is put on the flow phenomena in a rim cavity downstream of rotor blades. The experiments are conducted on a rig simulating a engine HP-turbine in which cooling effectiveness distributions as well as velocities, turbulence quantities, pressure and temperature profiles are measured. Numerical calculation, especially at a full 3D, unsteady solution level, can lead to satisfactory predictions in fluid and mass transfer inside the cavity. Both experimental and numerical results indicate that large turbulence stresses near the rotor disk intensify turbulent diffusion across the cavity and consequently axial distribution of the cooling effectiveness inside the cavity becomes uniform. In order to obtain an adequate distribution of cooling effectiveness across the rim cavity and to suppress the turbulence level near the rotor surface for more efficient cooling, a novel cooling method is developed using numerical simulation. The disk-front and -rear cavities are then redesigned according to the new cooling strategy and integrated in the test rig. Experimental results verify a significant advance in cooling performance with the new method.

scholarly journals Investigations on the effect of different influencing factors on film cooling effectiveness under the injection of synthetic coolant

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jianlong Chang ◽  
Xinlei Duan ◽  
Yang Du ◽  
Baoquan Guo ◽  
Yutian Pan
Keyword(s):  
Film Cooling ◽  
Elliptical Hole ◽  
Synthetic Jet ◽  
Cooling Effect ◽  
Flow Structures ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Flow ◽  
Cooling Method ◽  
Strong Controllability

AbstractBy combining the synthetic jet and film cooling, the incident cooling flow is specially treated to find a better film cooling method. Numerical simulations of the synthetic coolant ejected are carried out for analyzing the cooling performance in detail, under different blowing ratios, hole patterns, Strouhal numbers, and various orders of incidence for the two rows of holes. By comparing the flow structures and the cooling effect corresponding to the synthetic coolant and the steady coolant fields, it is found that within the scope of the investigations, the best cooling effect can be obtained under the incident conditions of an elliptical hole with the aspect ratio of 0.618, the blow molding ratio of 2.5, and the Strouhal number St = 0.22. Due to the strong controllability of the synthetic coolant, the synthetic coolant can be controlled through adjusting the frequency of blowing and suction, so as to change the interaction between vortex structures for improving film cooling effect in turn. As a result, the synthetic coolant ejection is more advisable in certain conditions to achieve better outcomes.

Unsteady Forces in Last Stage LP Steam Turbine Rotor Blades With Exhaust Hood

2016 ◽  
Author(s):  
Romuald Rzadkowski ◽  
Jan Surwiło ◽  
Leszek Kubitz ◽  
Piotr Lampart ◽  
Mariusz Szymaniak
Keyword(s):  
Numerical Study ◽  
Flow Analysis ◽  
Turbine Rotor ◽  
Rotor Blades ◽  
Steam Turbines ◽  
Exhaust Hood ◽  
Low Frequencies ◽  
Unsteady Forces ◽  
Relative Contribution ◽  
Last Stage

Several high vibration amplitude problems have been reported regarding the slender last stage blades of commercial LP steam turbines. This paper presents a numerical study of unsteady forces acting on rotor blades using ANSYS CFX. A 3D transonic viscous flow through the stator and rotor blades with an exhaust hood was modelled. The last stage was modelled as a full blade annulus, so that the axial, radial and circumferential distribution of flow patterns and blade forces could be examined. An unsteady flow analysis was conducted on a typically designed last stage and exhaust diffuser, with measured and calculated downstream static pressure distribution as the outlet boundary condition. The results showed that under off-design conditions, vortices occurred in the last stage and diffuser. Unsteady aerodynamic forces were found at high frequencies (stator passing frequencies) and low frequencies (generated from asymmetric pressure distributions behind the rotor), with the relative dominance of these forces/frequencies shifting as a function of radial span. An FFT analysis was carried out. Three sections were investigated: the hub, midspan and peripheral (tip) section. The steady pressure behind the rotor blade was compared with experimental results in the LP last stage behind the rotor blades and in a specified cross-section of the exhaust hood. The lower frequency unsteady forces had a higher relative contribution towards the tip of the blade.

Film Cooling Flow by Double Rows of Compound Angle and Compound Angle Shaped Holes

2013 ◽  
Author(s):  
Farzad Bazdidi-Tehrani ◽  
Pegah Pezeshkpour
Keyword(s):  
Film Cooling ◽  
Reasonable Agreement ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Cooling Effectiveness ◽  
Cooling Flow ◽  
Flow And Heat Transfer ◽  
Cooling Method ◽  
Simplec Algorithm ◽  
Compound Angle

The present paper describes a three-dimensional finite volume numerical simulation of turbulent flow and heat transfer over a flat plate embedded with four different configurations of film cooling jet holes. Recently, more advanced techniques are introduced to improve the effectiveness of film cooling method such as the Compound Angle Shaped Holes (CASH). The first two studied configurations in this article comprise double rows of staggered compound angle holes. The presented final configurations encompass double rows of the CASH geometry, with inline and staggered arrangements, consecutively. The second order upwind scheme is employed for the discretization of equations and the pressure-velocity coupling is performed by using the SIMPLEC algorithm. Moreover, the k-ω shear stress transport turbulence model is applied for the flow simulation. Present results on the compound angle holes show that the span wise-averaged cooling effectiveness is higher when 6D span wise hole spacing is employed as compared with 7.8D spacing. Results have emerged that the double rows of staggered CASH geometry display higher cooling effectiveness than that of the inline arrangement. Furthermore, comparison of the present spanwise effectiveness and ratio of Stanton numbers with the available experimental data shows reasonable agreement for the first and second configurations.

Numerical Study on Effects of Density Ratio on Film Cooling Flow Structure and Film Cooling Effectiveness

2017 ◽  
Author(s):  
Eiji Sakai ◽  
Toshihiko Takahashi
Keyword(s):  
Shear Layer ◽  
Film Cooling ◽  
Numerical Study ◽  
Density Ratio ◽  
Hairpin Vortices ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Flow ◽  
High Density Ratio ◽  
Cooling Hole

To understand film cooling flow fields on a gas turbine blade, this paper reports a series of large-eddy simulations of an inclined round jet issuing into a crossflow. Simulations were performed at constant momentum ratio conditions, IR = 0.25, 0.5, 1.0 and Reynolds number, Re = 15,300, based on the crossflow velocity and the film cooling hole diameter. Density ratio, DR, is changed from 1.0 to 2.0, and effects of the density ratio on vortical structures around the film cooling hole exit and film cooling effectiveness are investigated. The results showed that the vortical structure of the ejected jet drastically changes with varying density ratio. When the density ratio is comparatively small, hairpin vortices are formed downstream of the hole exit. On the contrary, when the density ratio is comparatively high, the formation of the hairpin vortices is suppressed and jet shear layer vortices are formed on side edges of the cooling jet. The jet shear layer vortices conveys the coolant air to the wall surface. As a result, higher film cooling effectiveness is obtained at comparatively high density ratio conditions compared to comparatively low density ratio conditions. Additional simulations were performed to discuss a possibility of an improvement in the film cooling effectiveness by controlling the formation of the jet shear layer vortices.

Aeroelastic Analysis of Last Stage LP Steam Turbine Rotor Blades With Exhaust Hood for Various Non-Nominal Regimes

2018 ◽  
Author(s):  
Romuald Rzadkowski ◽  
Vitaly Gnesin ◽  
Lubov Kolodyazhnaya ◽  
Ryszard Szczepanik
Keyword(s):  
Pressure Distribution ◽  
Steam Turbine ◽  
Gas Flow ◽  
Element Model ◽  
Turbine Rotor ◽  
Ideal Gas ◽  
Rotor Blades ◽  
Exhaust Hood ◽  
Flow Through ◽  
Last Stage

Presented here are the numerical calculations of the 3D transonic flow of an ideal gas through an LP steam turbine last stage with exhaust hood, taking into account blade oscillations. The approach is based on a solution to the coupled aerodynamic-structure problem for 3D flow through a turbine stage using the partially integrated method. The blade oscillations and loads acting on the blades are a part of the solution. An ideal gas flow through the stator and moving rotor blades with periodicity on the whole annulus is described by unsteady Euler conservation equations, integrated with the Godunov-Kolgan explicit monotonous finite-volume difference scheme and a moving hybrid H-H rotor blade grid. The structural analysis uses the modal approach and a 3D finite element model of a blade. The proposed algorithm allows for the calculation of turbine stages with an arbitrary pitch ratio of stator and rotor blades, taking into account unsteady-load induced blade oscillations. The pressure distribution behind the rotor blades was non-uniform on account of the exhaust hood. As a result of the fluid-structure interaction and exhaust hood induced nonsymmetrical pressure distribution behind the rotor blades, the first blade mode was no longer bending but bending-torsion.

Experimental Characterization of Film-Cooling Effectiveness Near Combustor Dilution Holes

2005 ◽  
Author(s):  
J. J. Scrittore ◽  
K. A. Thole ◽  
S. W. Burd
Keyword(s):  
Film Cooling ◽  
High Momentum ◽  
Complex Flow ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Flow ◽  
Thermal Fields ◽  
Flow Phenomena ◽  
Film Cooling Holes ◽  
Low Speed Wind Tunnel

Cooling combustor chambers for gas turbine engines is challenging, given the complex flow and thermal fields inherent to these modules. This complexity, in part, arises from the interaction of high-momentum dilution jets required to mix the fuel with film cooling jets that are intended to cool the combustor walls. This paper discusses the experimental results from a combustor simulator tested in a low-speed wind tunnel that includes both the dilution jets and film-cooling jets. The specific purpose of this study is to evaluate the influence that the dilution jets has on the film-cooling effectiveness. Infrared thermography was used to measure surface temperatures along a low thermal conductivity plate to quantify the adiabatic effectiveness from an array of film cooling holes with the presence of dilution holes. To further understand the flow phenomena, thermocouple probes and laser Doppler velocimetry were used to measure the thermal and flow fields, respectively. Parametric experiments indicate that the film cooling flow is disrupted along the combustor walls in the vicinity of the high-momentum dilution jets. In fact, a significant penalty in cooling effectiveness of the combustor is observed with increased dilution jet penetration.

An Experimental Investigation Into the Effect of Wakes on the Unsteady Turbine Rotor Flow

1985 ◽  
Vol 107 (2) ◽  
pp. 458-465 ◽  
Author(s):  
A. Binder ◽  
W. Fo¨rster ◽  
H. Kruse ◽  
H. Rogge
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Turbine Rotor ◽  
Rotor Blades ◽  
Air Turbine ◽  
Flow Phenomena ◽  
Unsteady Effects ◽  
Yaw Angle ◽  
Insight Into ◽  
Rotor Flow

Detailed measurements were carried out near and within a turbine rotor using the Laser-2-Focus velocimeter. Testing was performed in a single stage cold air turbine at off-design conditions with a stator outlet Mach number of approximately 0.8. Instantaneous and averaged results of the velocity, the yaw angle, and the turbulence intensity provided information on the rotor flow field. This report describes the periodical and random unsteady effects of the stator wakes impinging on the rotor blades. In particular the constant unsteadiness contours clearly disclose the development of the wakes cut by the rotor blades. The objective of the study was to gain more insight into unsteady flow phenomena affecting losses, heat transfer, and related problems.

A Comparison of Tip Gap Loss Sensitivity for Shrouded vs. Unshrouded Turbine Rotors

2019 ◽  
Author(s):  
William V. Banks ◽  
Ali A. Ameri ◽  
Robert J. Boyle ◽  
Jeffrey P. Bons
Keyword(s):  
Numerical Study ◽  
Flow Characteristics ◽  
Aircraft Engine ◽  
Turbine Rotor ◽  
Rotor Blades ◽  
Tip Clearance ◽  
Blade Loading ◽  
Shrouded Rotor ◽  
Grid Independence ◽  
Stage Efficiency

Abstract A numerical study was conducted to evaluate the loss sensitivity of shrouded vs. unshrouded turbine rotor blades. Accuracy is demonstrated with a series of grid independence studies. Application of the methods is performed through various studies related to the effects of shrouding a High-Pressure Turbine (HPT) rotor blade for a NASA-specified N+3 timeframe single-aisle aircraft engine at takeoff conditions. Flat, Recessed, and Shrouded rotor configurations are evaluated at tip clearances from 0.25% to 4% of blade span. Mach # distributions, near-tip blade loading, and other flow characteristics are examined. Plots of stage efficiency vs. tip clearance are presented, with trends compared to available experimental data. It is shown that for the imposed boundary conditions, the addition of a shroud improves stage efficiency and significantly reduces sensitivity to tip clearance at higher clearance fractions. A casing recess is also shown to slightly increase sensitivity to tip clearance for tip clearances greater than 0.5%. Total pressure loss profiles vs. blade span are also compared, providing insight into the mechanisms behind the performance of the three configurations.

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